<!DOCTYPE html>
<html lang="en">

<head>
<meta charset="UTF-8">
 <meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
<script src="../vue.js"></script>
</head>

<body>
<div id="app">

 姓:<input type="text" v-model="firstName"><br>
 名:<input type="text" v-model="firstName"><br>
 全名:{{firstName.toUpperCase()+"-"+lastName.toUpperCase()}}
 {{fullName}}
 </div>
 <script>
    Vue.config.productionTip=false;

    const vm =new Vue({
        el: "#app",
        data() {
            return {
                firstName:"",
                lastName:"",
                fullName: vm.firstName +"-" +vm.lastName
            }
        }
    })
 
 </script>
</body>

</html>